Kiln.



PATBNTED AUG.'21, 1906.

A. E. TRUESDELL.

KILN.

APPLIUATION FILED DBG. 5. 1904.

3 SHEETS-SHEET 1.

ed., wasHmaraN, n. c.

PATBNTED AUG. 21, 1906.

A- E TRUBSDBLL.

KILN.

. is essential that the heat generated for a matiran @STATES PATENT ortica..

KILN.

Specification of Letters Patent.

Patented Aug. 21, 1906.

Application filed December 5, 1904. Serial No. 235,438.

To all whom t may concern:

Be it known that I, ARTHUR E. TRUES- DELL, a citizen of the United States, residing at Pittsfield, in the county of Berkshire and State of Massachusetts, have invented an Improvement in Kilns, of which the following description, in connection with the acl companying drawings, is a specification, like l characters on the drawings representingA like parts.

This invention relates to that type of kiln wherein a moderate burning temperature is essential; and its object is to provide means whereby the temperature of the products of combustion and the volume and duration of the flame may be controlled or regulated, according to the character of the fuel used for generating the heat.

In the burning of lime, for which my present invention is particularly well adapted, it

terial length of time shall not exceed 1,000O centigrade, for if a greater temperature than this is produced the silicates and other fusible impurities present in the lime-rock will fuse and form a slag on the outside of the rock, which prevents the proper burning and results in an inferior product. Furthermore, it is essential to commercial operation that this heat should be distributed through a comparatively large body of material, or, in other words, that the flame caused by the combustion of fuel should be one of large volume. Accordingly it has been customary heretofore to use wood as the fuel, for while wood has a comparatively low calorific power, yet it yields sufficient heat to effect the calcination of the lime-rock, and the flame therefrom is of sufficient volume to result in evenly burning the lime. It is sometimes impracticable or impossible to obtain sufficient wood for the purpose, owing to the increasing scarcity and high price of this fuel. Fuel such as coal, coke, oil, or gasA as ordinarily burned in air during the process of combustion generates an intense local heat, but does not generate a sufficient volume of flame to properly burn the lime. The result is that where these fuels are used in burning lime the portion of the lime-rock adjacent to the fuel during its combustion is overburned, while portions of lime-rock at some distance do not receive suflicient heat to become properly burned. Furthermore, the intense heat generated by burning these fuels causes the rapid j deterioration of the fire-brick linings of the combustion-chambers.

It is the object of my present invention to provide a novel form of kiln in which fuelsuch as coal, coke, Sac., may be advantageously used, and I accomplish this by providing means whereby the available heat units are liberated and used at the temperature most suitable to the material being calcined or fired without producing such extremes of temperature in the burning portions of the kiln as to cause the over or under burning of the product.

In applying my invention to a kiln of the ring-and-oven type I place between each two adjacent kiln-chambers one or more furnaces or generating-chambers, which are so constructed that they act as gas-producers-that is, producer-gas is generated in them, and the gas after being generated in any one is delivered to the succeeding kilnchamber or kiln-chambers. Vhen this gas enters the kiln-chambers in which the material is to be burned, it is commingled with air which is delivered to said chambers in order that combustion may take place, the amount of air being so delivered and regulated, according to the character and amount of gas delivered, that a flame of the requisite temperature will be formed to properly burn the material in the kiln-chamber. By controlling the amount of air and the points where it is delivered to and commingled with the producer-gas the burning-flame may be stretched out, as it were, not only through the neXt succeeding kiln chamber, but through two or three succeeding kiln-chambers, if necessary, to produce the flame of the right temperature and volume. The temperature of the flame may be further regulated and modified by introducing steam into the gases prior to their combustion in the kiln-chamber. This introduction of steam may or may not be suitable with all classes of product, but with lime it is an advantage, because it not only modifies the temperature of the flame, but assists in the liberation of CO2 from the stone, which latter operation takes place at a lower temperature when steam is present in the gas. The heat units in the fuel may therefore be liberated at the temperature most suitable for burning the material being fired and at widely-distributed points, so that an even burning may be effected with little or no deterioration of the IOO `removed from the chambers 20.

brick linings of the kiln. The generating l chambers or furnaces are arranged in series l with the kiln-chambers, so that the current l passing through the successive chambers can be taken from one kiln-chamber to the next kiln-chamber through the intermediate generating chamber or chambers.

I prefer to. employ downdraft generatingchambers-that is, generating-chambers in which the draft through the fuel therein is downwardly instead of upwardly-and for this purpose each generating-chamber has an inlet port orduct at its upper end connecting `with the upper end of the preceding kilnchamber and a discharge port or duct at its lower end communicating with the succeeding kiln-chamber.

In the drawings, which show one form of my invention, Figure 1 is a top or plan view of a kiln embodying my invention. Fig. 2 is a transverse vertical section through the kiln shown in Fig. 1. Fig. 3 is a top plan view of a portion of the kiln on the same scale as Fig. 2, said view showing the kiln-chambers and generating-chambers open and the covers y Fig. 4 is a section, on an enlarged scale, on the line y y, Fig. 3. Fig. 5 is asection, on an enlarged scale, on the line a cb, Fig. 3. Fig. 6 is adetail hereinafter described. Fig. 7 is a section on an enlarged scale, on the line c c, Fig. 1, Fig. 8 is a horizontal section through Fig. 7. Fig. 9 is a detail of the portable forced-draft apparatus. Fig. 10 is an end'view of Fig. 9.

The kiln shown in the drawings is of the ring-and-oven type, and therefore the kilnchambers are arranged in series and are connected together consecutively.

I have illustrated herein twenty kiln-chambers, and they are designated by a, a2, a3, a4, a5, a, to (L20 and are arranged in two rows or series. Between the two rows of kiln-chambers is a smoke-flue 300, to which all or a part of the kiln-chambers may be connected and into which the products of combustion are delivered. Suitable draft in the smoke-flue 300 maybe induced in any suitable way, either mechanically, as by a fan or steam-jet, or by means of a chimney 30a. I prefer to use both a chimney and a steam-jet, as will be more fully explained hereinafter. Situated between each two adjacent kiln-chambers are one or more (two in this embodiment of my invention) furnaces for generating gas, which furnaces I will hereinafter refer to as generating-chambers. The generating-chambers corresponding to the kiln-chamber a are designated by U, those corresponding to the kiln-chamber a2 are designated b2, those corresponding to the kiln-chamber a3 are designated b3, &c. The particular construction of the generating-chambers will be hereinafter described more at length.

I have illustrated the kiln as provided with a tunnel 3 beneath each row of kiln-chambers,

ceases' and each kiln-chamber has an upper chargingopening through which said kiln-chamber may be charged with unburned material, and a lower discharging-opening, through which the burned material can be discharged into a car 5 on a track 4 in one of the tunnels. The charging-opening is atthe top of each kiln chamber and is adapted to be closed by a suitable cover 12, and the discharging-openingis herein illustrated as in the bottom of each chamber and as closed by one or more bricks or blocks 6, which are supported on wedge-shaped strut members 7, the latter resting on a plate 8, Which is detachably clamped to the flange 9 of a collar 10, surrounding the discharging-opening. The closures for the charging and discharging openings are so constructed that when in place said openings are closed to the passage of. air. Above the kiln-chambers I propose to place an elevated trackway 13, on which a carrier 14 may run for the purpose of conveying the material to the kiln-chamber which is to be fired. With this construction of kiln-chamber the operation of charging and discharging is greatly facilitated by the action of gravity.

The generating-chambers are each provided with grate-bars 15, on which the fuel rests, andan open top, through which the fuel is delivered to the chamber. As stated above, these generators are of the downdraft typethat is, the draft passes downwardly through them during the process of burning the fuel rather than upwardly through them. For this purpose each generating-chamber has near its top an inlet or draft port 21, which leads into a duct or passage 20, communicating with the top of the preceding kiln-cham- ICO ber, and at its bottom a discharge-port 24, i

which leads into the following kiln-chamber. I prefer to arrange the mouth or delivery end of the discharge-passage 24 near the cooler part of the kiln-chamber, and for this purpose provide each chamber with the false bottom 26, which forms the top of a portion of said discharge-duct 24, as best seen in Fig. 5. Between each pair of generating-chambers is a vertically-extending by-pass duct 27, which communicates at its upper end with the preceding kiln-chamber through a duct or port 28 and at its lower end with the following kiln-chamber through a port or duct 29. (See Fig. 4.) Each of the by-pass ducts 27 is provided with a suitable valve by which it may be closed, which in this form of my invention is merely a brick or block 30, which can be slid over the upper end of the duct 27. The inlet-ports 21 for each generating-chamber are. controlled by suitable valves, preferably in the form of blocks 23, which can be moved to cover or uncover said ports, as desired. Each of the chambers 2O is provided with a suitable removable cover 3 1, and either all or a portion of the kiln-chambers are connected with the smoke-flue 300 by means of TIG sessie?,

short 'l'lues 39, which may be opened or closed by the valves 32, as seen in Figs. 7 and 8. Each chamber 2O is large enough to accommodate a portable device for creating forced draft in the generating-chamber, the device herein shown being a jet-blower or steam-jet apparatus such as is shown in Fig. 9, which consists of a sleeve or hollow member '60, the bore of which is choked slightly, as at 61, and a steam-jet pipe 62 to deliver steam into the open end of said sleeve. I propose to use two of these steam-jet apparatus, one in chamber at each side of any given kiln-chamber, and said apparatus will preferably be made portable, so that they can be advanced from one chamber to another as the fire advances around the kiln. Each steam-jet pipe 62 is capable of being detachably secured to a steam -pipe 63, connected to any suitable boiler. (Not shown.)

The operation of the kiln as thus far described is as follows: Assuming that the kilnchamber a4 is about to be fired, that the kilnchamber a3 has just been iired, that the kilnchamber @17 has just been discharged and is open for recharging, and that the kiln-chamber als is being discharged, the valve 32 is opened to connect one of the chambers 20, corresponding to the kiln-chamber al, with the smoke-flue 300, and the'valves 23 of both said chambers 20 are placed so as to close the inlet-ports 2l, leading to the generatingchambers b", and a steam-jet is placed in each of the two chambers 20, corresponding to the kiln-chamber c3. With this arrangement the draft induced by the chimney and steam-jet draws fresh air into the kiln-chainber als, from which it passes through the generating-chambers bw into the kiln-chamber al", and thence through the generatingchambers 1220 and kiln-chamber azointo a crossduct 35, which connects the kiln-chamber (L20 with the generating-chambers b. Said current of air then passes on through the various kiln-and generating chambers until the kilnchamber a3 is reached. The burning of the material in the kiln-chamber a4 is effected by the gas produced in the generating-chambers b4, and therefore, going on the assumption above made, it will be understood that said generating-chambers b4 are filled with coke or similar fuel which is being gasified. When the current of air reaches kiln-chamber (L3, it becomes divided, one portion being forced b v the steam-j ets through the generating-chambers b4 and the other portion passing directly from the kiln-chamber a3 to the kiln-chamber a4 through the by-pass 27. The air which is forced through the generating-chambers b4 becomes converted into producer-gas as it passes through the fuel-bed in the said generating-chambers, and this gas is delivered to the kiln-chamber a4 through the dischargeducts 24. The amount of gas thus produced depends upon the amount of air which is valves 23.

forced through the generating-chambers, and this can be regulated by manipulating the The producer-gas is delivered to the kiln-chamber a4 at two points, both beneath the unburned material therein, and as it passes upwardly through and distributes itself throughout the unburned material in said chamber it becomes commingled with the air which is delivered to said kiln-chamber through the by-pass duct 27, and combustion takes place. The burning of the material is effected partially by the heat of the incandescent fuel in the generating-chambers, which heat is transmitted througn the partition between said chambers and the kiln-chamber and partly by the combustion of the producer-gas, which combustion takes place when said gas becomes commingled with the air delivered through the by-pass duct 27. From the kiln-chamber c4 the gases pass through chambers t5 a5 a, &c., and finally emerge from the kiln-chamber a16 through the duct 39 into the smoke-flue 30, said gases on their passage through kiln-chambers af a a7,&c., giving up their heat to the unburned material therein.

By means of the construction of kiln above described and the character of gas used it is possible to get the desirable even temperature in the kiln-chamber a4, for it will be noted that the gas, which is hotter than the air, is introduced into the kiln-chamber at the point naturally the coolest, being farthest from the generator, and the air which is at a lower temperature than the gas is introduced at the rearmost place, close to the generator. Both the air and gas are introduced into the kiln-chamber beneath the unburned materialtherein, and as they rise through said material they become 'gradually mixed, and combustion is thereby made gradual and is evenly distributed.

l find it of advantage in the operation of the kiln to introduce more steam into the primary air, or that which is drawn through the generating-chamber, than is supplied by the steam-jets7 as such added quantity of steam not only gives a lower temperature in the generating-chamber, but also enriches the gas produced therein by forming a mixture of water-gas and producer-gas. This excess steam may be provided in a variety of ways, either by taking the steam from a central steam-generating plant and introducing it into the proper generating-chambers or by providing portable steam-generators which can be used at each generating-chamber or in any other suitable way. In the form of the invention herein shown I use a portable steam-generator, which comprises a steamgenerating pan 6,5, attached to the cover 66 of the generating-chamber by a pipe 67, through which the pan is supplied with water as needed. (See Fig. 6.) These steam-generating covers can be shifted from one gen- IOC ITS

. from the supply-pipe 46 into the ducts 24.

Said distributing-pipe is provided with nipples 49, which connect with pipes 500, extending into the space beneath the grates 15. The amount of steam thus delivered through the distributing-pipe 48 will depend somewhat on the character of the rock being burned and on the temperature which is desired and other attendant circumstances.

The combustion in the kiln-chamber may be modified or controlled by the valve 30, which controls the admission of air to said chamber, and the valve which controls the admission of steam into the gas. Excess of air shortens the flame and localizes the heat, while deficiency of air stretches out the flame, even to the extent of more than one kiln-chamber, and thus distributes the heat. The admission of steam into the gas lowers the temperature of the flame. Hence by means of the construction above described the temperature is not only controlled, but the chamber is evenly heated in all parts.

Whenever during the operation of the kiln it is observed that the material in any kilnchamber is completely burned, it becomes necessary to start a fresh fire in the generating-chambers for the succeeding kiln-chamber, at which time, if desirable, the valve 32 may be closed, and the next in circuit Vmay be opened to include fresh chambers in the circuit. At this time the generating-chambers abandoned may be isolated from the air-current by closing the valves 23 and their contents discharged at any later time, or their contents may be immediately discharged and while hot screened and used in starting the generators which are next to be fired. In any case the valve 30 is opened wide to afford free circulation of air to the following generator.

To facilitate the operation of drawing the Ylire while the coal is still hot, I have so constructed my generating-chambers that the contents thereof may be discharged through an opening in the bottom either onto the ground or into a car. For this purpose I so construct each generating-chamber that the grate-bars 15 rest at one end upon a shoulder 17 and at the other end on a supporting-strut 4or brick 18, which in turn rests on a plate 16,

supported by wedge-shaped blocks 51.

These wedge-shaped blocks are situated in the throat or dischargeopening and rest on plates 19, which are detachably clamped to an outturned flange on the collar 50, surrounding the discharge-opening. With this construction the drawing of the fire involves merely the removal of the clamps which hold the plate 19 to the flange, for as soon as said clamps are removed the supporting-blocks 51, strut 18, grate-'bars 15, and material in the generating-chamber all drop through the discharge-opening by the action of gravity. After the fuel has been discharged the joint between the plate 19 and the collar 50 is sealed, so as to prevent air being drawn in at this point. l

In practice I propose to extend each pipesection 500 through one of the wedge-shaped supporting-struts 51 and to make such pipesection rigid with said strut.

On -v firing the next pair of generatingchambers the two steam-jet apparatus are removed from the ducts 2O in which they are located and placed in ducts 2() leading into the generating-chambers to be red, and after these generating-chambers are fed with fuel the steam-j ets are started, which results in the production of gas and combustion of same, as above described. Meanwhile chambers of material are being emptiedand filled in the rear, and so the operation of the kiln is continuous.

Some of the advantages of the downdraft type of generating-chambers over the updraft type are, first, that the top of the kiln remains cooler, and consequently radiation from the kiln is less; second, the covers are cooler, and hence less liable to be broken; third, the handling of the kiln is less arduous; fourth, the gas is better distributed in the kiln-chamber, fifth, it is much easier to observe the process of burning, and, sixth, better control of the temperature in the generating-chambers is secured.

Some of the advantages of a kiln in which the generating-chambers alternate with the kiln-chambers instead of a kiln having a single outside generator from which the gas is distributed to the various kiln-chambers are, first, the saving of the heat units lost in radiation from the single generator and piping therefrom, second, the introduction of gas and air into the kiln-chamber to give an even heat is facilitated g third, deposit of soot in the pipes is avoided, and, fourth, the air for the generator is preheated, and energy to that extent is utilized.

Although the construction herein lillustrated is that which I deem to be preferable, yet the details of the kiln may be varied in many ways without departingfrom the invention.

The kiln herein shown is of the ring-andoven type; but my invention is not limited to this type of kiln, for with appropriate modi- ICO `fications many of the features of the invention could be embodied in kilns of the ring type and in other forms of kilns.

Having fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. In a ring-and-oven kiln, a plurality of kiln-chambers, and a similar number of gasgenerating furnaces, each furnace having its outlet-flue or discharge-port connected to one kiln-chamber, and its inlet or draft port connected to another kiln-chamber.

2. In a kiln, a plurality of kiln-chambers and a corresponding number of downdraft gas-generating furnaces, each furnace being connected with the corresponding kiln-chamber.

3. In a kiln, a'plurality of kiln-chambers, and a downdraft gas-generating furnace for each kiln-chamber, each furnace having a gas-outlet port opening into the bottom of the corresponding kiln-chamber beneath the material therein. I

4. In a kiln, a plurality of kiln-chambers, and a gas-generating furnace for each kilnchamber, each furnace having an outlet-port to deliver gas to the bottom of the corresponding kiln chamber beneath the material therein.

5. In a kiln, a plurality of kiln-chambers, separate means adjacent each kiln-chamber to generate gas and deliver it to said chamber beneath the material therein.

6. In a kiln, a plurality of kiln-chambers, and means adjacent each kiln-chamber to generate gas and deliver it to the bottom of said chamber beneath the material therein.

7. In a kiln, a plurality of kiln-chambers, and a downdraft gas-generating furnace for each kiln-chamber, each furnace having an outlet-duct communicating with the bottom I of the corresponding kiln-chamber beneath the material therein.

8. In a kiln, a kiln-chamber, a downdraftv furnace having an outlet-duct communicating with the bottom of said chamber beneath the material therein, and means to admit steam to the top of the furnace, whereby water-gas is generated.

9. In a kiln, a kiln-chamber, a downdraftfurnace having an outlet-duct communicating with the bottom of said chamber beneath the material therein, said furnace being constructed to generate producer-gas, and means to admit steam to the top of the furnace, whereby combined producer-gas and watergas is generated. y

10. In a kiln, a plurality of kiln-chambers, a furnace situated between eachtwo adjacent kiln-chambers and arranged to deliver gas to one of said kiln chambers and having a valved passage connecting with the other kiln-chamber, said furnace being separate from the kiln-chambers. Y

11. In a kiln, a plurality of kiln-chambers,

a downdraft-furnace between each two adj acent kiln-chambers, a valved inlet-port connecting the top of each furnace with the preceding kiln-chamber, and an outlet-port connecting the bottom of each furnace with the succeeding kiln-chamber.

12. In a kiln, a series ofkiln-chambers, a furnace between each two adjacent kilnchambers, each furnace being connected to the chambers on either side thereof, and a by-pass duct directly connecting adjacent kiln-chambers.

13. In a kiln, a series of kiln-chambers, a downdraft-furnace betweenV each two adjacent kiln-chambers, each furnace having an inlet-duct at its top communicating with the preceding kiln-chamber and an outlet-duct at its bottom connecting with the succeeding kiln-chamber, and a by-pass duct directly connecting adjacent kiln-chambers.

14. In a kiln, a series of kiln-chambers, a downdraft-furnace between each two adjacent kiln-chambers, each furnace having a valved inlet-duct at its top communicating with the preceding kiln-chamber, and an outlet-duct at its bottom connecting with the succeeding kiln-chamber, and a valved bypass duct directly connecting adjacent kilnchambers. n

15. In a kiln, a plurality of kiln-chambers, a furnace for each kiln-chamber, said furnace being constructed to generate a mixture of producer and water gas, and means to commingle steam with the gas mixture as it is delivered from any furnace to the kiln-chainber.

16. In a kiln, a plurality of kiln-chambers, a downdraft-furnace between each two adj acent kiln-chambers, each furnace having a l discharge-opening leading to the bottom of the succeeding kiln-chamber, and an inletopening leading to the top of the preceding kiln-chamber, means to admit steam to the top of each furnace, and means to deliver steamto the outlet-port of each furnace.

17. In a kiln, a plurality of kiln-chambers, and a furnace for each kiln-chamber, each furnace having an upper charging-opening and a lower discharging-opening through which the fire may be drawn.

18. In a kiln, a plurality of kiln-chambers, and a downdraft-furnace for each kiln-chamber, each furnace having an opening in its top through which it may be charged and an opening in its bottom through which the fire may be drawn. j

19. In a kiln, a plurality of kiln-chambers, each having an upper charging-opening and a lower discharge-opening, and a furnace for each kiln-chamber, each furnace having an upper charging-opening and a lower discharging-opening.

20. In a kiln, a plurality of kiln-chambers and a gas-producing furnace for each kilnchamber, each furnace having an upper IOO .charging-opening and a lower dischargingopening, and removable grates within each gas-producing furnace and situated over the discharging-opening.

21. ln a kiln, a plurality of connected kilnchambers each having an upper opening through which material is delivered to said chamber, and a lower opening through which the burned material is discharged therefrom, and removable closures for said yopenings constructed when in place to prevent the passage of air through either opening while the kiln is in operation.

22. ln a kiln, a plurality of kiln-chambers having communication with each other, and each having a charging-opening in its top and a discharge-opening in its bottom, and removable closures for said openings constructed when in place to prevent the passage of air through said openings while the kiln is in operation.

23. In a kiln, a plurality of kiln-chambers having communication with each other and each having a charging-opening in its top and a discharge-openingin its bottom, removable closures for said openings constructed to prevent the passage of air therethrough while the kiln is in operation, a trackway eX- tending beneath all the chambers, an overhead trackway above the chambers, 'and a carrier on said latter trackway, whereby the action of gravity may be used to aid in the handling of the material burned in the kiln.

24. In a kiln, a plurality of kiln-chambers, a gas-producing furnace for each kiln-chamber, each furnace having an upper chargingopening and a lower discharging-opening, a cover for each discharge-opening, and a set of grate-bars within each furnace, one end of each set of grate-bars being supported by the cover for the corresponding discharge-opening, whereby when the cover is removed the grate-bars and fire may be removed through said opening.

25. In a kiln, a plurality of kiln-chambers, a gas-generating furnace for each kiln-chamber but separate therefrom, and means independent from the furnace whereby heated airmay be delivered to that kiln-chamber in which the material is to be burned.

26. In a kiln, a plurality of kiln-chambers, a gas-producing furnace between each two adjacent kiln-chambers, each furnace being connected to the chambers on either side thereof, and means independent from the furnace to deliver heated air to that furnace in which the material is being burned.

27. ln a kiln, a kiln-chamber having two inlets, one for gas and the other for air, said inlets being situated at widely -separated parts of the kiln, and means to delivergas to one inlet and air to the other.

28. In a kiln, a kiln-chamber having an inlet for gas and a separate inlet for air, and

means to deliver gas to the gas-inlet and air y to the air-inlet, said inlets being separated from each other and situated at different parts of the kiln-chamber.

29. ln a kiln, a plurality of kiln-chambers, a gas-generating furnace for each kiln-chamber, and an apparatus to force lair into the furnace in which gas is being produced for the purpose of making gas therein, said apparatus being portable and capable of removal from one furnace to another.

30. ln a kiln, a plurality of kiln-chambers, a gas-generating chamber for each kiln-chamber, a cover for the gas-generating-chamber in which gas is being generated, said cover having steam-generating means associated therewith.

31. In a kiln, a plurality of kiln-chambers,

a gas-generating furnace for each kiln-chamber, a portable forced-draft apparatus to force air into the fuel in the furnace in which gas is being produced.

32. In a kiln, a plurality of kiln-chambers, a gas-producing furnace between each two adjacent kiln-chambers, each furnace being connected to the kiln-chambers on either side thereof, and a portable apparatus to force air into the fuel in that furnace in which gas is being produced whereby the gas is generated.

38. In a kiln, a plurality of kiln-chambers, a gas-generating furnace for each kiln-chainber, a portable steam-jet apparatus adapted to be associated with the furnace in which gas is being produced and force air into the fuel-bed therein for the production of gas.

34. In a kiln, a plurality of separate kilnchambers, a gas-generating chamber between each two adjacent kiln-chambers and connected to each, means to establish a current of air through the chambers in succession, and means to divide the current of air into two currents-having any desired relative volume prior to its entrance into the gas-generating chamber in which combustion begins, one of said currents passing through the said gas-generating chamber and the other being carried around the latter and reuniting with the first-named current at a point forward of the said gas-generating chamber, whereby combustion is only partially completed in said chamber and is completed at a point farther on.

35; In a continuous kiln, a series of separate kiln-chambers, a gas-generating chamber between each two adjacent kiln-chambers, means to establish a current of air throu h the chambers in succession, means to re uee to any degree the amount of air which passes through that gas-generatin chamber in vwhich gas is being enerate whereby the combustion in said c amber is only partially completed, and means to restore the maximum current of air to a chamber beyond.

36. In a continuous kiln, a series of connected kiln-chambers, a gas-generating cham- IOO ber between each two adjacent kiln-chambers, means to establish a current of air through said chambers in succession, which current normally is sui'licient to complete combustion in any one of the gigas-generating chambers, and means to shunt any desired portion of said air-current around the generating-chamber in which gas is being generated, and deliver said shunted portion of air to a kiln-chamber beyond, whereby the amount of air which passes directly through the gas-generating chamber in which gas is being produced is insufficient to complete combustion therein. l

37. In a continuous kiln, a plurality of kiln-chambers, a gas-generating chamber be tween each two adjacent kiln-chambers, means to regulate the quantityof air supplied to that generating-chamber in which gas is being produced so that the gases which are being generated have a high heat value, means to supply to the gas at a point farther along an added quantity of air, and means to regulate this quantity of air so that the flame is attenuated and combustion completed.

3S. In a continuous kiln, a plurality of kiln-chambers, a gas-generating chamber situated between each two adjacent kiln-chambers and connected to each, means to establish a current of air through the kiln-chambers and gas-generating chambers in succession, means to shunt a portion of said current around the gas-generating chamber in which gas is being produced and deliver said shunted portion to a kiln-chamber beyond, and dampcrs or valves to regulate the relative amounts of air shunted around and delivered to said gas-generating chamber.

39. In a kiln, a plurality of separate kilnchambers, a gas-generating chamber between each two adjacent kiln-chambers and connected to each, means to establish a current of air through the kiln-chambers and gasgenerating chambers in succession, regulating devices by which the quantity of air supplied to that gas generating chamber in which gas is being produced can be regulated so that the gas produced therein is of high heating value, and means to supply to the gas at a point farther on an added quantity of air, whereby combustion is completed and the flame attenuated.

40. In a continuous kiln, a plurality of kiln chambers, a downdraft furnace between each two adjacent kiln-chambers and connected to each, means to -establish a current of air through the kiln-chambers and furnaces in succession, and means to shunt a portion of said current around the furnaces in which gas is being produced and deliver said shunted portion back into the main current at a point farther on.

41. In a continuous kiln, a plurality of kiln chambers, a downdraft furnace, between each two adjacent kiln-chambers and connected to each, means to establish a current of air through the chambers and furnaces in succession, a by-pass duct directly connecting successive kiln-chambers, and valves controlling said various by-pass ducts, whereby a portion of the air may be shunted around the furnace in which the gas is being produced, nd delivered to the succeeding kiln-charm In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses,

ARTHUR E. TRUESDELL.

Witnesses:

Louis C. SMITH, BERTHA F. HEUsER. 

